I was hoping you were going to tell me about them, saying they were awesome!!
In all seriousness, I have very little experience with them, but given the average litter size and number of litters per year, with a conservative projection of 15-20 pups per pair, I think you could easily breed the pet version towards the goal of a "meatier" version, though I would argue the MOST important factor sounds like it would be easy breeding females who have successful litters no matter what their body type. I would have to taste the meat to become motivated to do it myself I think. In my area the rats would kill them, and I would have to house them indoors or in very secure cages.